 | This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (October 2012) |
| Gascondian | |
|---|---|
| Usage information | |
| Celestial body | Earth |
| Regional usage | Regional |
| Time scale(s) used | North American |
| Definition | |
| Chronological unit | Age |
| Stratigraphic unit | Stage |
The Gasconadian Stage is the 1st stage of the Ordovician geologic period in North America and of the Lower Ordovician Canadian Epoch, coming immediately after the Late Cambrian Trempealeauan and preceding the middle Canadian Demingian Stage. The Gasconadian is equivalent to the European Tremadocian and roughly to the Skullrockian of the Ibexian series.
The Gasconadian is named for the Gasconade Formation of Missouri, named in turn for the Gasconade River, and is represented by the Tribes Hill Formation in New York state and by the upper Bliss Fm and the Sierrite Ls of the El Paso Group in southern New Mexico and west Texas.
The Gasconadian is a common term in the paleontological and stratigraphic literature of the previous century, whether used simply for a span of time or for strata laid down during that time.